1. Technical Field
The disclosure relates to an actuator position calculation device, an actuator position calculation method, and an actuator position calculation program, used for driving or the like of a sample stage of a scanning probe microscope.
2. Related Art
A scanning probe microscope measures a surface shape of a sample by making a probe installed at a front end of a cantilever close to or contact with the sample surface. For measurement modes of the scanning probe microscope, there are known (1) a contact mode in which an atomic force between the probe and the sample is maintained to be constant and a surface shape of the sample is measured, and (2) a method (hereinafter, appropriately referred to as a “dynamic force mode (DFM measurement mode)”) in which the cantilever is forced to be vibrated around a resonance frequency by a piezoelectric element or the like, and a shape of the sample is measured using the fact that an amplitude of the probe is reduced by intermittent contact between both of the two when the probe is made close to the sample.
The scanning probe microscope is provided with an actuator including: a piezoelectric element which scans the sample in an xy (plane) direction; and a piezoelectric element which scans the sample in a z (height) direction, and the sample is placed on a surface of a sample stage which is disposed on the actuator. A voltage applied to the piezoelectric element is in proportion to a displacement of the piezoelectric element to an extent, and thus height information of the sample surface can be calculated from a voltage applied to the piezoelectric element. However, operational characteristics of the piezoelectric element have hysteresis or creep, and thus it is hard to obtain an accurate position of the piezoelectric element from the applied voltage. Therefore, a technique has been developed in which a displacement of the piezoelectric element in the Z direction is detected using a sensor provided separately from the piezoelectric element (refer to JP-A-9-80060).